I killed my bike one snowy winter day last year. Had the gloves, pants liner, and jacket liner going in stop-and-go traffic until the bike died. The battery wasn't dead, but didn't have enough to start or keep the bike going. I've since gotten a couple of voltmeters wired in and found that anything below about 2500 rpm produces just over 12 volts. Not enough to run all the heated gear, light bar and high beam (I ride hi beam during the day and lite bar all the time). Putting the battery on a charger and keeping the bike at 3k or turning all non-essentials off in town keep things going.
If yours is completely dead, check the connections and look for a bad ground at the battey. It took me about 30-40 minutes to kill the bike, but there was still some left in the battery. If all the connections are good, you may want to look at possibly a bad battery.